1. Field of the Invention
The present invention generally relates to a headrest of adjustingly inclinable type for use with an automotive seat, which includes an inclination adjustment mechanism wherein a lock may be engaged with and disengaged from a stationary gear element, such as a ratchet gear, to permit adjustable inclination of the headrest at a desired angle for supporting a seat occupant's head. In particular, the invention is directed to an unlocking mechanism of a push button type operable for unlocking such inclination adjustment mechanism provided in this sort of headrest.
2. Description of Prior Art
Among various inclinable headrests for automotive seat, there is known a headrest of inclinable type having a push-button-type unlocking mechanism provided therein, wherein an unlocking push button is movably provided in a wall of the headrest and operatively connected with an inclination adjustment mechanism provided within the headrest. The inclination adjustment mechanism, for example, comprises a stationary gear element, such as a ratchet gear, fixedly provided to the headrest, and a lock gear vertically rotatable for engagement with and disengagement from the stationary gear element. The lock gear is operatively connected with the push button, so that, when a user presses that push button, the lock gear is rotated upwardly out of engagement with the stationary gear element to thereby release the headrest from a locked state. Therefore, the user can adjustingly incline the headrest forwardly and rearwardly in order to set the headrest at a desired angle of inclination
As disclosed for example in Japanese Laid-Open Patent Publication No. 1-164310 (JP 1-165310 A), there is known an inclinable headrest of the above-stated kind having an unlocking push button movably provided in one lateral wall of a body of the headrest which is covered with a trim cover assembly. In this prior art, the layer of the trim cover assembly overlies the push button, for which reason, the push button itself is not exposed and invisible from the outside. A marking is therefore affixed on the outer surface of trim cover assembly at an area where the push button exists under the trim cover assembly, so that a user can recognize the location of the push button and can push such marked area to cause depression of that push button for unlocking an inclination adjustment mechanism provided in the headrest. But, the user must strongly push that marked area against the tension of the trim cover layer until the push button is completely pressed to unlock the inclination adjustment mechanism.
With regard to the inclination adjustment mechanism, for example Japanese Laid-Open Patent Publications Nos. 8-224139 (JP 8-224139 A) and 2012-162123 (JP 2012-162123 A) show a well-known ratchet-type inclination adjustment mechanism for use with an inclinable headrest, in which a ratchet gear is fixedly provided to the headrest and a lock gear is vertically rotatable for engagement and disengagement with and from the ratchet gear, thereby allowing adjustment of inclination of the headrest in forward and rearward directions.
In contrast to the above-described inclinable headrest of the type wherein a push button is invisibly disposed inside of the headrest, there is also known an inclinable headrest of the type having a push button partially exposed and visible from the outside, which enables a user to directly press the push button to release the headrest from a locked state. Reference is now made to FIG. 2 which shows an inclinable headrest of this kind in the present invention. While the headrest of such outwardly-exposed-push-button type is well known, the FIG. 2 is used provisionally in this description of prior art to show a typical known outer configuration of headrest wherein an outwardly exposed push button is provided, for the sake of clarity, since no prior-art material is found to clearly show such outwardly exposed push button, on the side of the inventors and assignees involved in the present invention. Namely, as understandable from FIG. 2 just by way of example, there is indeed a known inclinable headrest having an unlocking push button (at 2) provided in one lateral wall of the headrest so as to be partially exposed and readily accessible from the outside, and any person skilled in the art knows that particular type of inclinable headrest.
However, as one of technical problems with such push-button unlocking type of headrest, it has been difficult for a worker to quickly and precisely connect a push button from the outside to the inclination adjustment mechanism stated above. For example, as shown in the afore-stated JP 1-164310 A, the inclination adjustment mechanism is disposed within the headrest, and a connecting end portion of that inclination adjustment mechanism, adapted for connection with a push button, is located far deeply in a hole formed in the body of the headrest. Hence, a worker can not visually ascertain a precise position of such connecting end portion from the outside. If the worker connects a push button through the afore-said hole to the connecting end portion from the outside, he or she must manage to connect the push button with the connecting end portion within the hole, depending on his or her imagination and fingers' feeling, which is a troublesome time-consuming problem. Therefore, it has been impossible for the worker to quickly and precisely connect the push button with the invisible connecting point in the headrest.
As a solution to that problem, the afore-said connecting end portion of headrest inclination mechanism may be extended to a point near to the outside of the afore-said hole in which the push button is slidably stored, in an attempt to enable a worker to easily connect the push button therewith, which is for example disclosed in Japanese Laid-Open Patent No. 2001-46170 (JP 2001-46170). This prior-art literature shows an unlocking mechanism for allowing a headrest to be folded downwardly by a manual pushing operation, which includes a laterally slidable lever element and an operating portion integral therewith, the operating portion extending outwardly form that lever element. According thereto, pushing the operating portion causes the lever element to slidingly move laterally of the headrest to actuate an unlocking element, thereby allowing the headrest to fold downwardly. From the drawings of this JP 2001-46170, it is seen that the lever element is disposed in a frame and the operating portion of the lever element passes through a ringed portion of the frame and extends to a point near to the outside of the headrest, and therefore, any person skilled in the art can readily understand that such outwardly extended operating portion is to be situated within a through-hole defined in an upholstery layer of the headrest adjacent to the ringed portion of the frame and that a push button is movably stored in such through-hole, though not shown. Therefore, any person skilled in the art will readily notice that, in assembly, an end of the operating portion will be disposed near to an outwardly facing side of the through-hole and a worker will insert a push button in the through-hole and connect the push button with the end of the operating portion disposed within the through-hole.
However, even with such construction, a precise connection between the push button and the end of the operating portion can not be visually observed by the eyes of the worker, because the push button itself is inevitably to conceal the end of the operating portion in relation to the hole when the worker begins to insert the push button in the through-hole and connect the same with the end of the operating portion. Thus, it is still annoyingly required for the worker to use his or her imagination and fingers' feeling to complete connection of the push button with the operating portion. Further, the extended operating portion is not supported by any supporting element, with the result that there is a great likelihood that the operating portion will be bent or dislocated from a predetermined position during assembly of the mechanism and headrest, prior to that operating portion being connected with the push button. In that case, it is extremely difficult for a worker to connect a connecting region of the push button with the operating portion. Still further, such provision of extended operating portion results in a greatly increased dimensions of the unlocking mechanism on the whole. In this regard, the headrest previously stated in the JP 1-165310 A also results in such increase of internal mechanisms and parts in a headrest. According to such JP 1-165310 A, in a lateral wall of an internal frame accommodating the mechanisms, all mechanical parts associated with a push button are collectively provided, with the result that a whole of the internal frame is inevitably formed so large that the lateral wall thereof is disposed near to a corresponding lateral side of an upholstery of the headrest. This is indeed necessary to locate the mechanical parts adjacent to a hole formed in that lateral side of upholstery, the hole being so adapted that the push button is movably stored. Hence, in this prior art, such large formation of internal frame is inevitably required, and the internal mechanical parts associated with the push button have to be disposed exteriorly of the lateral wall of the internal frame adjacent to the hole in which the push button is movably stored.
As a consequence of the foregoing conventional defective factors, it has been impossible for a worker to quickly and precisely connect a push button to an adjustment mechanism provided within a headrest, which prevents rapid assembly of the headrest, and also, the sizes of internal mechanical parts associated with the push button are inevitably increased.